A 'documentation coverage' of grunt-ngdocs

Question

To generate the documentation of my project I use ng-docs:

https://github.com/m7r/grunt-ngdocs

I would like to have a report of which elements (controllers, directives,...) are not yet documented using grunt-ngdocs.

Ideally this report could be added directly into the documentation, or in a way to locate easily the files which are missing documentation. Does such a grunt task or plugin exist?